A Sweet Treat for the Brain

Posted by Vani Taluja on February 13, 2025 in Cognition, Neuroscience, NeuWrite, Valentine's Week | Leave a comment

We all need a little treat sometimes – maybe on a special occasion, maybe after a long day, or maybe just as a pick-me-up in the afternoons. If you’re a chocolate lover like me, this treat might be a lindor truffle or a mocha latte. Many research studies have found that people show improvements in cognitive function after having chocolate, but how does this sweet treat lead to such an effect? Here, we take a deeper look into how chocolate may benefit the brain. Since NeuWrite’s previous article about how chocolate can affect both mood and cognitive performance in 2014 [1], today’s article will cover how these changes might be occurring under the surface (or in this case, under the skull).

BACK TO THE BEAN

So where does this magical product come from anyway? Chocolate products are derived from cocoa beans – the seeds within the fruit of the Theobroma cacao L. tree. The name “Theobroma” is derived from Greek, roughly translating to “Food of the Gods” [2] (which needs no further explanation if you’ve ever had chocolate yourself). Once pods are collected from the tree, the cocoa beans are separated from the rest of the fruit and undergo a fermentation and drying process (Figure 1). At this stage, specialized cold-pressing methods can make cocoa beans into a powder called cacao, which is the purest form of commercially available cocoa bean. However, this process is expensive, and the resulting cacao is very bitter. A cheaper and more common alternative is to process the cocoa beans through roasting and pressing with high-heat to create cocoa solids, additionally creating cocoa butter as a byproduct. Cocoa solids are ground into a powder to create cocoa powder, which typically includes added sugars to cut the bitterness.

Instead of pressing and grinding the cocoa solids into a powder, they can be recombined with cocoa butter through a process called conching. Briefly, conching evenly recombines the butter and the solids while simultaneously aerating the mixture, creating a silky smooth texture. The resulting product is called chocolate liquor (where liquor means “liquid”, rather than the alcoholic definition), which can be thought of as unsweetened baking chocolate. Next, other sweeteners and milk products are added, and the chocolate bar as we know it is finally produced. The amount of chocolate liquor that goes into the bar relative to dairy and sweeteners is the percentage displayed on the label, from dark chocolate (~60% or higher) to milk chocolate (~55% or lower). White chocolate contains no chocolate liquor (and therefore no cocoa solids), and is only considered chocolate because it is made from cocoa butter and has a similar texture.

The nutritional elements of chocolate come from both the cocoa solids and cocoa butter in different forms. Cocoa solids contain many minerals, including potassium, magnesium, copper, and iron, as well as antioxidant compounds called polyphenols [4]. Antioxidants are considered especially healthy because they can reduce oxidative stress, or the daily wear and tear on cells in the body. Cocoa butter constitutes the fatty acid content [4], which has been shown in many studies to improve overall cardiovascular health such as reducing blood pressure, improving blood flow, or even reducing the risk of cardiovascular disease [5]. One study of almost 92,000 Americans found that chocolate consumption of any kind was correlated with reduced rates of mortality, both from cardiovascular disease but also from neural conditions such as Alzheimer’s disease [6]. Findings like this have led many researchers to shift focus from how nutritional elements in chocolate affect cardiovascular function and overall health to how they might be directly affecting the brain. Lots of research has been done correlating chocolate consumption with improvements in cognitive performance [7, 8], but questions still remain about if eating more chocolate independently relates to cognitive improvements and how this effect could be occurring in the brain.

THE HEART-BRAIN LOVE TRIANGLE

Since we know that chocolate is linked to positive effects on the heart, how can we be certain that the effects we see in the brain are not just a side effect (Figure 2)? In other words, how can we disentangle chocolate’s effects on the brain versus chocolate’s effects on the heart if we’re finding changes in both at the same time? A study in 2016 [9] sought to answer this by determining if chocolate intake over long periods was associated with increased cognitive function, even after controlling for cardiovascular, lifestyle, and dietary factors. By controlling for these “life factors,” this experiment uniquely captured how chocolate consumption most directly impacts cognitive ability, rather than how chocolate consumption impacts something (such as heart health) which in turn impacts cognitive ability. The researchers grouped 968 participants into levels of chocolate eaters: less than once per week (rare chocolate eaters) or at least once per week (regular chocolate eaters). Next, they tested cognitive function through a variety of tasks, such as measures of memory and reasoning. Finally, they used extensive questionnaires to collect information about life factors that could contribute to their cognitive scores, including consumption rates of different types of foods, medical history, socioeconomic status, and depression symptoms to name a few. This information was distilled into a list of what they considered the 12 most relevant factors: age, sex, education, total cholesterol, LDL-cholesterol, glucose, hypertension, daily food intake (across all categories), and 4 specific food group intake categories (meats, dairy, vegetables, and alcohol).

The team found that regular chocolate eaters had significantly higher scores on every measure of cognitive ability, reinforcing the relationship between consumption and cognitive function. This relationship was still strong even after each of the 12 life factors were controlled for. Such findings suggest that the connection between chocolate consumption and cognitive improvements is legitimate, and not simply a side effect of other health benefits of chocolate, like cardiovascular benefits. Furthermore, since this study looked at chocolate consumption over multiple years, rather than just within the timeframe of the study, it seems that these effects are stable over time. This implies that the cognitive effects of chocolate consumption are more likely due to something in the brain changing gradually over time, rather than short-lived reactions to the chemical compounds of chocolate entering the bloodstream.

BEAN TO THE BRAIN

Now that we know chocolate has an impact on the brain, two questions follow: where in the brain are these changes occurring and how do these changes specifically impact cognitive performance? A 2023 study [10] investigated these exact questions. The researchers in this group had previously found that increasing the concentration of cocoa polyphenols – the antioxidant compounds in cocoa solids – with “darker” chocolates had a positive effect on both cognitive performance and concentration on the task [11]. In this study, they repeated their previous experiment and additionally used functional MRI to assess changes in location and level of brain activity after chocolate consumption. They gave 26 participants dark chocolate with either high or low concentrations of polyphenols and measured brain activity while subjects performed a simple cognitive task, both 25 minutes and 50 minutes after consumption.

The researchers found two brain regions in the left hemisphere that had significantly different levels of activity between the high concentration (HC) and low concentration (LC) groups: the dorsolateral prefrontal cortex and the supramarginal gyrus. For context, the dorsolateral prefrontal cortex is generally related to working memory and organization, whereas the supramarginal gyrus is associated with language processing and recognition of emotions (see [12] for more information on these, and more, brain regions). Generally, both regions are involved in complex cognitive processing.

As shown in Figure 3, brain activity in both regions increased over time for the LC group (in blue), while the opposite was true for the HC group (in red). Despite these differences, there was no difference in performance on the cognitive task for either group. The authors suggest that the decreased brain activity over time in the HC group might reflect increased “cognitive efficiency.” In other words, the increased polyphenols might allow the brain to consume less cognitive resources and energy to do the same cognitive task with the same performance level, thus making the brain more efficient. However, more research is still needed to figure out how the polyphenols in particular contribute to this effect. Combining this finding with the previous study about chocolate consumption over multiple years, it appears that regular chocolate consumption over time is likely to improve cognitive performance by increasing long-term cognitive efficiency.

One limitation of this study was that increasing the cocoa polyphenols in chocolate also increases many other compounds, such as caffeine and theobromine (which gives chocolate its bitterness). Because of this, we cannot disentangle if the effects seen are driven by the cocoa polyphenols themselves, or one of these other compounds that was additionally changed.

TREAT YOURSELF

Lucky for us, research on the various impacts of chocolate is ongoing, so hopefully the magical elements that make chocolate so special will be revealed soon! In the meantime, I would say we have good reason to treat ourselves to some dark chocolate every now and then, and especially this valentine’s day.

REFERENCES

[1] Galinato M. “In a Chocolate-y Mood?” NeuWrite SD. 2014. https://neuwritesd.org/2014/02/14/in-a-chocolate-y-mood/

[2]  Rusconi M, Conti A. Theobroma cacao L., the Food of the Gods: a scientific approach beyond myths and claims. Pharmacol Res. 2010;61(1):5-13. https://doi.org/10.1016/j.phrs.2009.08.008 

[3] The difference between cacao, cocoa, and chocolate: a cocoa bean’s journey. Pantry Food Co. 2020. https://pantryfoodco.com/blogs/news/the-difference-between-cacao-cocoa-and-chocolate-a-cocoa-bean-s-journey

[4]  Torres-Moreno M, Torrescasana E, Salas-Salvadó J, Blanch C. Nutritional composition and fatty acids profile in cocoa beans and chocolates with different geographical origin and processing conditions. Food Chem. 2015;166:125-132. https://doi.org/10.1016/j.foodchem.2014.05.141

[5] Grassi D, Desideri G, Ferri C. Blood pressure and cardiovascular risk: what about cocoa and chocolate?. Arch Biochem Biophys. 2010;501(1):112-115. https://doi.org/10.1016/j.abb.2010.05.020

[6]  Zhong GC, Hu TY, Yang PF, et al. Chocolate consumption and all-cause and cause-specific mortality in a US population: a post hoc analysis of the PLCO cancer screening trial. Aging (Albany NY). 2021;13(14):18564-18585. https://doi.org/10.18632/aging.203302

[7]  Martín MA, Goya L, de Pascual-Teresa S. Effect of Cocoa and Cocoa Products on Cognitive Performance in Young Adults. Nutrients. 2020;12(12):3691. Published 2020 Nov 30. https://doi.org/10.3390/nu12123691

[8]  Nehlig A. The neuroprotective effects of cocoa flavanol and its influence on cognitive performance. Br J Clin Pharmacol. 2013;75(3):716-727. https://doi.org/10.1111/j.1365-2125.2012.04378.x

[9] Crichton GE, Elias MF, Alkerwi A. Chocolate intake is associated with better cognitive function: The Maine-Syracuse Longitudinal Study. Appetite. 2016;100:126-132. https://doi.org/10.1016/j.appet.2016.02.010

[10] Sasaki A, Kawai E, Watanabe K, et al. Cacao Polyphenol-Rich Dark Chocolate Intake Contributes to Efficient Brain Activity during Cognitive Tasks: A Randomized, Single-Blinded, Crossover, and Dose-Comparison fMRI Study. Nutrients. 2023;16(1):41. Published 2023 Dec 21. https://doi.org/10.3390/nu16010041

[11] Sasaki A, Mizuno K, Morito Y, et al. The effects of dark chocolate on cognitive performance during cognitively demanding tasks: A randomized, single-blinded, crossover, dose-comparison study. Heliyon. 2024;10(2):e24430. Published 2024 Jan 11. https://doi.org/10.1016/j.heliyon.2024.e24430

[12] Guy-Evans O. Brodmann Areas Of The Brain. Simply Psychology. 2023. https://www.simplypsychology.org/brodmann-areas.html